Technical Field
This invention relates generally to hand-held tape dispensers. More particularly, this invention relates to a hand-held dispenser for adhesive tape of the sort which is used for ordinary household and office purposes. Specifically, this invention is directed to a tape dispenser which has an improved plastic cutter assembly for severing BOPP (Biaxially-Oriented Polypropylene) adhesive tape, a protrusion for supporting a first region of the tape when a second region thereof is being severed, and a brake mechanism for halting rotation of the tape roll.
Background Information
Adhesive tape is commonly used in households and offices to secure articles together. Typically, this tape is between 1 and 2 cm in width. For the purposes of the present invention, this type of adhesive tape will be referred to as “household tape”. Household tape is generally sold and available in two formats: in rolls that are typically sold in boxes or already installed in small handheld tape dispensers. In North America, the majority of the household tapes in use are made using two different film substrates, namely, acetate and BOPP (Biaxially-Oriented Polypropylene).
Acetate film includes a backing of cellulose acetate, which comes from wood pulp and/or cotton fibers, treated with acetic acid and anhydride. One side of the film is treated with a release agent. The construction of the film is very brittle and it has very poor pull strength; therefore, the slightest incision in the substrate tends to tear the film apart. There are few commercial sources of this film in the world and it is, therefore, a relatively expensive raw material. Furthermore, to minimize the naturally higher risk of breaking the web of film, causing exorbitant wastage rates in production, during the coating and converting processes, both activities are managed at a very slow pace.
By contrast, BOPP film is manufactured using an extrusion process. The extruded film is stretched significantly from a 1 meter width (±39″) at extrusion to a 9 meter wide (±354″) finished roll. Such film is not brittle and does not tear easily, usually requiring a sharp blade to incite a tear. The 9 meter wide roll is slit into smaller manageable widths ranging from 1.27 meter (50″) to 2 meters (79″), to accommodate desired machine capacities. BOPP is manufactured much more widely and efficiently, therefore, it is a much more cost-effective film to procure while generating significantly more manageable wastage levels.
To facilitate the increased penetration of good quality BOPP film in North American household tapes in recent years, metal cutters have been installed in the cutters of the typical hand-held tape dispensers to ensure a satisfactory experience for the consumer. The increased strength of the film makes it more difficult to cut and the metal cutters have proven to be more successful at accomplishing this task than previous plastic cutters. Until the development of the present invention, which shall be described hereinafter, nobody has successfully designed a hand-held tape dispenser that includes plastic teeth which can tear BOPP adhesive film without compromising the film's performance. In those instances where BOPP film is able to tear on a plastic cutter, the actual film has had to be modified during the converting process by serrating the film's edges using a special knife, a process termed score-cutting. Though this ensures that the user is more easily able to dispense the tape on a plastic cutter, this type of tape product tends to fail industry tests under normal laboratory conditions with respect to tensile strength and elongation.
U.S. Pat. No. 6,612,474 discloses a hand-held tape dispenser that is suitable for dispensing acetate type adhesive tapes. U.S. Pat. No. 6,612,474 is assigned to the same assignee as the present matter. In the tape dispenser disclosed in U.S. Pat. No. 6,612,474, the teeth on the plastic cutter have a relatively small height as it does not take much to tear the acetate tape when dispensing the product. However, this same patented dispenser is less able to consistently and satisfactorily dispense BOPP adhesive tape as this type of tape tends to stretch on the teeth instead of being cut thereby.
There is therefore a need in the art for a tape dispenser including a plastic cutter assembly that is able to more consistently and satisfactorily dispense BOPP-based adhesive tapes.